1. Field of the Invention
The invention relates to a method of monitoring the condition of soiling and/or calcification of heat exchangers in heating installations comprising a primary circuit containing a heating medium, in particular heating water, and a secondary circuit containing a medium to be heated, in particular service water, the heating-up process of the medium to be heated being controlled on the basis of operational data, namely of temperatures of the heating medium and the medium to be heated as well as the triggering data for pumps for conveying the heating medium and/or the medium to be heated through the heat exchanger by means of a heating-up control device. Further, the invention relates to a heating installation which is provided with a monitoring device putting into practice the method according to the invention. In connection with the method according to the invention and the corresponding heating installation, emphasis must in advance be put on the fact that the invention can be used in heating installations as well as in cooling installations. Although the focus of this is a corresponding heating installation so as to avoid any wording of the claims that would be difficult to understand, it goes without saying that a corresponding monitoring method will also make use of the invention in connection with a cooling installation.
2. Background Art
A basic problem with heating installations having a primary circuit containing a heating medium such as heating water and a secondary circuit containing a medium to be heated, for instance service water resides in that, while the installation is in service, the heat exchanger thermally coupling the two circuits may be clogged by coagulation, accumulation of mud, soiling, calcification or similar deposits as a result of physical or chemical reaction during the change of temperature of the heating medium or the to-be-heated medium while the heat exchange takes place, since the mentioned soiling and calcification may deposit on the heat exchanger surfaces and/or in the supply conduits to the exchanger surfaces. As a result, the parameters on the basis of which the heating installation is designed, such as flow resistances, flow rates, pressures, temperatures, energy conditions and performances, K-values etc., change permanently, which affects the service behavior of the heating-up control unit negatively. This jeopardizes any impeccable functioning of the heating installation in conformity with its design.
To avoid the afore-mentioned problems it is necessary in due time to replace or at least clean the heat exchanger or such other parts of the installation as are subject to soiling and/or calcification. Since, however, the rate by which soiling and/or calcification deposit highly depends on local conditions such as water quality, there is no possibility in advance to determine the time by which malfunction will occur. Nevertheless, such deposits should be recognized at an early stage for any subsequent damages such as a total breakdown, interruptions in operation, excessive energy consumption, the destruction of parts of the installation etc. to be prevented. Moreover, a heat exchanger for instance is easier to clean when total clogging of the flow channels has not yet occurred.
To solve the problem outlined above, there are monitoring systems that monitor the degree of soiling of heat exchangers actively. These systems are for instance based on measuring the pressure differences between the supply and the discharge of the heat exchanger on the secondary side. Monitoring the flow throughput per time unit that decreases with the increase in soiling has been put into practice.
Such monitoring systems have the disadvantage that the parts of the installation responsible for measuring such as pressure gauges or flow-meters are also in contact with the medium to be heated and soiling or clogging may occur within them, too. This falsifies the corresponding measured values.
Moreover, such monitoring systems require separate measuring devices which would not be needed for the actual control of the heating installation. In this regard, the structural requirements for the heating installation are considerably increased by these monitoring systems.
Further, the values monitored may be variable by reason of the different designs of heating installations, which requires an adaptation of the monitoring device to the respective installation.